There are many heating and cooling systems on the market and many of these rely on fossil fuels. With the ever increasing demand for more environmentally friendly systems various alternative systems based on sunlight or water have been proposed such as for example, photovoltaic, solar thermal electricity generators, hydroelectricity, wave power and bio-fuels.
An issue common to all solar-driven renewable energy conversion devices, some hydro-driven devices, and wind turbines is that they cannot operate “on demand” as the sun does not always shine, the seas are not always high and the wind does not always blow. This means that at some times these so-called intermittent renewable sources will generate electricity which cannot be easily integrated into their corresponding local electricity grids, and as such there have been a number of storage solutions proposed.
The thermal energy storage system, proposed in WO 2009/138771 converts surplus electrical energy from intermittent renewable sources into heat or cool when available, store the so-converted heat or cool in a thermal store, and then make it available as useful heat or cool on demand using phase change materials (PCMs) to effect the energy conversion via their inherent solid-liquid phase changing properties.
In known thermal energy storage systems, comprising heat batteries containing phase change materials, the phase changing material within each battery, will during its most active energy storage and release phase, change from solid to liquid and vice versa over about a 6° C. temperature range. To date, it has only been possible to predict the charge state of any such battery by using a large number of temperature sensors inside the batteries, which is neither practical nor cost effective.
For practical application, in high-demand, commercial or industrial situations in particular, thermal energy storage systems including phase change materials which have determinable efficiency measures would be highly desirable to enable effective predictions of energy reserves for planning and energy management purposes.
It is an object of at least one aspect of the present invention to provide a thermal storage system having integral means for providing residual energy measures.
It is an object of at least one aspect of the present invention to provide a thermal storage system having integral means for efficient charging of batteries within an assembly.
It is an object of at least one aspect of the present invention to provide a thermal storage system having integral means for predicting the charge state of batteries within an assembly.
It is an object of at least one aspect of the present invention to provide a thermal storage system having integral means for determination of relative energy levels within batteries within an assembly.
It is an object of at least one aspect of the present invention to provide a thermal storage system having integral means for protection of batteries within an assembly against over pressurisation. The Applicant has developed a novel and inventive thermal storage system comprising heat batteries having internal heat exchangers and PCMs wherein said system includes integral means for providing a variety of control measures including: overall system energy efficiency measures; measures of battery charging efficiency; determination of relative energy levels within batteries; and wherein said system provides protection of said batteries against over pressurisation.